Since the 1990s, members of the US House have shifted resources away from legislative functions to representational activities. We reveal this decline using an original dataset constructed from 236,000 quarterly payroll disbursements by 1,090 member offices for 120,000 unique staff between the 103rd and 113th Congresses, as well as interviews with former members and staff in Congress. These data allow us to test two plausible alternative explanations, one rooted in the centralization of legislative power over time and the other in conservatives’ desires to contract government power. We show that the decline in legislative capacity is symmetrical between and consistent within both parties, contrary to expectations rooted in asymmetrical, ideological sabotage. Additionally, this divestment occurs within incumbent member offices over time, accelerates when new members replace incumbents, and persists when majority control changes. We conclude that competition over institutional control and centralization of legislative functions motivates declining legislative capacity among individual members.